Spindle Seals and Heat Generation

[Anorak Bob]

Yesterday I needed to drill a some holes in a pair of grinding wheel nuts and I chose to use my dainty imperial Hercus mill for the task. ( The other mill, little but not dainty, is metric and this was an inch job.) Then I remembered why it has sat forlornly under a sheet for four or so years now. After a few minutes of running, the spindle in the mill's vertical head had become nearly too hot to touch. I had mentioned this in the Hercus forum a few years back and Bruce "Abratool" informed me that his mill's head ran cool. It ran cool because it had no seals. With no seals mine too runs cool. No seals would necessitate the wearing of a plastic raincoat or in Bruce's case, a wetsuit.

The original seals are single lipped, steel cored with a garter spring. With the springs removed the heat persists. Hercus used Flaseal 13297 seals. I replaced the originals with NAK seals. They measure 2.500" x 1.875" x 0.375". This morning I had a look for PTFE seals but without success.

I imagine Hercus used lipped seals on the head to retain the oil more than to exclude dust and swarf. The No.1 T and C grinder utilises labyrinth seals to do both but the spindle is horizontal.

Can anyone suggest an alternative to the lipped seal?

Bob.

[Neil317]

DIY labyrinth? Minimise the clearances, you should be fine.
Neil

[Machtool]

G'day Bob.

A Vee-ring might get you out of trouble. Because you can alter the axial position of the seal, you can play with seal contact pressure. The also have the joy of opening up when they are spinning, becoming more of a flinger than a contact seal.

They are nominally metric, but fit a wide tolerance range, so you can run them on Imperial shafts.

http://www.allsealsinc.com/pdfs/skfvringcatalog.pdf

Take a look at the VR1 style - #400450.You would squeeze that in there, and have it running on the seat of the original seal housing, or rework that front cover.

I retrofit these into some spindles. Those that run on CNC plasma cutters, that carry a spindle for drilling all so.

They work best against a hardened, fine surface finish face. I have them Ceramic HVOF sprayed, then ground and lapped. You wont need that at the speeds of a Hercus.

Regards Phil.

[Anorak Bob]

Hi Phil,


I did contact SKF when you suggested the possible use of their Vee Ring as an alternative to the revised additionally sealed Timken taper bearings in the T and C workhead. In the case of workhead there wasn't sufficient clearance available in which to shoehorn a seal. Sadly that remains an unresolved problem.


The vertical head is blessed with more space. Maybe a seal will fit without too much fooling around. I will have a close look at the seal you recommend.


Thank you.


Bob.

[Michael G]

Yesterday I needed to drill a some holes in a pair of grinding wheel nuts and I chose to use my dainty imperial Hercus mill for the task. After a few minutes of running, the spindle in the mill's vertical head had become nearly too hot to touch.

Have you tried slackening off the preload a little? I'm still wrestling with mine as there seems to be a fine point between too much (=too hot) and not enough(= spindle slop).

Michael

[nadroj]

Wave oil seals claim to run cooler than the usual type garter seal with a straight lip, as well as some other benefits.
Sealed bearings (when available) touch the metal surface very lightly, compared to garter seals.

Jordan

[Machtool]

I did contact SKF

SKF were sort of late to that party. I think they bought into some one, to get those seals on the books.

NAK do them, any of the other bearing companies should be able to get them.
http://nak.com.au/technical/NAK_VSealsInstallGuide.pdf

I'd probably have one sitting in my bearing cabinets, if you wanted one sent over to play with.

Regards Phil.

[Anorak Bob]

Wave oil seals claim to run cooler than the usual type garter seal with a straight lip, as well as some other benefits.
Sealed bearings (when available) touch the metal surface very lightly, compared to garter seals.

Jordan

Not always lightly enough Jordan. Another project requiring attention :doh:- http://www.woodworkforums.com/showthread.php?t=186175&p=1788512#post1788512


SKF were sort of late to that party. I think they bought into some one, to get those seals on the books.

NAK do them, any of the other bearing companies should be able to get them.
http://nak.com.au/technical/NAK_VSealsInstallGuide.pdf

I'd probably have one sitting in my bearing cabinets, if you wanted one sent over to play with.

Regards Phil.

If it is not too much of a pain in the neck I'd love to have a play Phil.:U

[Anorak Bob]

Have you tried slackening off the preload a little? I'm still wrestling with mine as there seems to be a fine point between too much (=too hot) and not enough(= spindle slop).

Michael

Michael,

There is next to no heat if the seals are absent.



Wave oil seals claim to run cooler than the usual type garter seal with a straight lip, as well as some other benefits.
Sealed bearings (when available) touch the metal surface very lightly, compared to garter seals.

Jordan

Not always lightly enough Jordan. Another project requiring attention http://d1r5wj36adg1sk.cloudfront.net/images/smilies/actions/doh.gif- http://www.woodworkforums.com/showthread.php?t=186175&p=1788512#post1788512


SKF were sort of late to that party. I think they bought into some one, to get those seals on the books.

NAK do them, any of the other bearing companies should be able to get them.
http://nak.com.au/technical/NAK_VSealsInstallGuide.pdf

I'd probably have one sitting in my bearing cabinets, if you wanted one sent over to play with.

Regards Phil.

If it is not too much of a pain in the neck I'd love to have a play Phil.http://d1r5wj36adg1sk.cloudfront.net/images/smilies/happy/biggrin.gif

[Michael G]

SKF were sort of late to that party. I think they bought into some one, to get those seals on the books.


We use SKF seals at work. Originally they were a company called Jetseal I think who were bought by Economos who were then bought by SKF. (At least that's what I picked up from one of the reps once)

Michael